Small Engines (Lawn Mowers, etc.): Troy Bilt tiller transmission oil, troy bilt tiller, pep boys

Question
I purchased a late-1970s/early-80s Troy Bilt Horse tiller a few weeks ago. I had to replace the carb (it was way past the point where a rebuild kit would work) and once I got it fired up, I changed the engine oil and drained the transmission oil. (looked just like Hershey's syrup)

According to the manual I downloaded from troybilt.com, it makes reference to using SAE 90 or SAE 140 gear oil. However, it doesn't mention whether it should be GL-1, GL-2, etc. Some of the chatter I've googled up seems to indicate that if you use GL-5 (which is readily available at Pep Boys) in a gearbox that wasn't designed for GL-4 or GL-5, you may damage brass or bronze hardware since there are some additives in GL-5 that react specifically with those metals.

Is there any truth to that? If so, I see that I can get a 35lb. pail of GL-1 from Aubuchon Hardware for $50 (plus $15 shipping) ... but that sounds excessive so I'd really like to know whether it's necessary.

Thanks in advance,
Dave

Answer
 Hello Dave:

 Go to Advance and get a Bottle of 80 w 90 Synthetic Gear Lube. The Gearbox of your tiller doesnt move fast enough to harm the Brass. That is true only for Automotive Applications where Heat is a Huge Factor. Hope this Helps.

 Good Luck

 Respectfully

 John